1. Field of the Invention
The present invention relates to a method for copying session information, a call control server for executing the method, and a program for copying session information.
2. Description of the Related Art
In information processing systems based on the World Wide Web (WWW), one service such as a ticket purchasing service is processed in response to a plurality of requests. In such systems, a function called session is used to clarify to which service processing status each request belongs. A server maintains session information. The session information includes information required for a service, including service processing statuses such as “reserved” and “paid”, user identifiers (IDs), addresses, names, and session IDs. A client sends a request along with the ID of each session to the server. Thus, the server can recover a service processing status. For example, when a user terminates and then resumes a process in a browser, items already entered can be automatically recovered by identifying a service processing status based on a session ID at the time of termination. Further, a mismatch can also be prevented from occurring between the true and recovered service processing statuses.
In order to improve the reliability of a WWW server having such session functions, a mechanism in which a plurality of WWW servers share session information has been widely used. For example, Japanese Unexamined Patent Application Publication No. 2006-146663 discloses a mechanism in which all application servers that form a cluster have session information regarding each application server. If a fault occurs in one of the servers, another server that shares the session information takes over the process.
Additionally, a system for implementing telephone functions using an Internet Protocol (IP) technology, which WWW is based on, has recently become widely available. This system uses a protocol called Session Initiation Protocol (SIP), in which messages are sent and received between a SIP server, a calling terminal, and a called terminal to establish a media session between the calling terminal and the called terminal. The messages include session information. The session information is copied and shared by a plurality of SIP servers.